Cool Page 2

But
a difficulty arose immediately. Kehren simply couldn’t find a small,
super-efficient, reasonably priced, production-type air-conditioner anywhere—at
least not one he was really satisfied with. So, with characteristic vigor,
he decided to take matters into his own hands and design his own unit.
This line of thinking took him straight to the Miami International Boat
Show and Motro, whose small, versatile company is open to new ideas and
manufacturing ventures. Within weeks the two men were working on an air
conditioning unit they hoped would run on half the current consumed by
most mainstream machines—or maybe even less. They opted for the comparatively
small, 6,000-Btu model because the size of their test platform, the 800-cubic-foot
interior of Kehren’s boat, was actually quite small and because they
were both aware of a critical but generally underutilized truth: Because
small, continuously operating A/C units remove more moisture from the
air than larger, intermittently running units, they offer higher comfort
levels at the same cabin temperature.

Kehren
and Motro did several things to boost the efficiency of their new 6,000-Btu
machine. First, they added a rotary compressor, which is quieter, smoother,
and more efficient than most piston types. Then they installed a high-quality
blower motor, again, quieter, smoother, and more efficient than many others.
And finally, after adding a top-of-the-line evaporator and precisely matching
it to an equally top-of-the-line condenser, they figured out how to conjoin
all these components in extra-savvy but proprietary ways. “It’s
not just high-end parts that’ll make this thing work,” Motro
opined at one point, “it’s how we’ll put them together.”

Reports
on the finished product were convincing enough to put me on a plane to
Miami and eventually to Kehren’s home, where the Harley awaited on
her waterside lift. My plan was to conduct a lengthy but simple experiment.
Kehren would turn on his new A/C system early in the afternoon, when the
Florida sun is typically at its hottest. After checking everything out
thoroughly, I’d proceed to keep tabs on the system through the ensuing
evening, and on into the next morning, to see if it indeed did what Kehren
and Motro claimed it would do.

The system I saw was not complicated. Kehren had interfaced a 2,000-watt Xantrex
PROsine 2.0 inverter with a battery bank consisting of one 12-volt Trojan
J185H deep-cycle battery paralleled with a pair of series-connected 6-volt
Trojan L16H batteries. Since the series-connected 6-volt batteries simply
doubled the voltage but did nothing to change amperage or capacity (measured
in amp hours, or AH), the cumulative rated capacity of the entire battery
bank, based on Trojan’s specifications, was 610 AH, a figure achieved
by simply adding 215 AH for the single 12-volt battery to 395 AH for the
two 6-volt batteries.

The
inverter, its control panel (with readouts for input and output voltage
and amperage), and the battery bank were stacked neatly on Kehren’s
dock, and the A/C unit was temporarily set up inside the boat, which remained
on the lift. Cooling water entered the evaporator via a ten-foot hose
trailing down into the canal and a small, 320-gph CAL A.C. pump that was
separate from the system as well as from the experiment. Pump installations
vary from application to application, and power draw is negligible anyway.
Heavy-duty wires connected the unit and the inverter. Before I flipped
the starting switch, I examined all hoses and wires to make sure there
was no extraneous power source hidden anywhere.